God designed us with the desire and hormones for sex. He created us that way: men have a very strong desire for women. Woman was created to be with Man. As long as a man is without a woman there will always be a sexual desire that exists in our bodies and there is absolutely nothing you can do to stop that. (In Genesis, God gave men the sexual desire for women. "Your desire will be for your husband, and he will rule over you." Genesis 3:16) Again, God put this desire in us. I can guarentee you that 99.9% of men in the world will have commited a sexual sin in all sins that exist and commit those sins most frequently out of all their sins. ("Things that cause people to sin are bound to come" LUke 17:1)
I say this because you are not alone at all. We are sinners and adultery, fornication, & sexual immorality are sins. Jesus died for all our sins: past, present, and future. Every single one of them. "Therefore, since we have been justified through faith, we have peace with God through our Lord Jesus Christ." Romans 5:1
To defeat temptation, DO NOT think about trying to resist the temptation. If you do that...then you will be more inclined to give into the temptation! You must change your attention to something else. Every time that temptation pops into your head...immediately think about something else that will completely submerse your attention in that. Turn your attention to something else you enjoy doing or have done recently like a job promotion or your favorite computer game or a math problem that you couldnt figure out...anything that can completely take over your mind's entire contemplation. The most important thing to do is PRAY every time you sense that temptation coming on. Ask God for the strength to overcome this temptation and He will. "For he will never give you a tempation that will overwhelm you" (forgot which verse)
You may feel confused over this "why you seem to keep losing to this sin"...I tell you that Paul has gone through the same thing...we all go through this paradox.
So I find this law at work; When I want to do good, evil is right there with me. For in my inner being I delight in God's law, but I see another law at work in the members of my body, waging war against the law of my mind and making me a prisoner of the law of sin at work within my members. What a wretched man I am! Who will rescue me from this body of death? Thanks be to God- through Jesus Christ our Lord!!
Romans 7:21-25
Brother, Jesus has died for your sins already and you know that you must be a slave to God, not a slave to sin. Have faith in God and pray for strength.
Praying for you.
It is God's will that you should be sanctified: that you should avoid sexual immorality; that each of you should learn to control his own body in a way that is holy and honorable.
1 Thessalonians 4:3
Pray and the Lord will be faithful.
The Lord is faithful, and he will strengthen and protect you from the evil one.
2 Thessalonians 3:3